CS265840B1 - A method for treating an epitaxial layer prior to measuring the epitaxial structure of indium phosphide - Google Patents

Abstract

Before the actual measurement, the substrate with the deposited epitaxial structure of indium phosphide is immersed in redistilled water heated to boiling point for one to two minutes.

Description

(57). Prior to the measurement, the substrate with the indium phosphide deposited epitaxial structure is immersed in redistilled water heated to the boiling point for one to two minutes.

CS 265840 Bl

265 840

The present invention relates to a method for treating an epitaxial layer prior to measuring the epitaxial structure of indium phosphide by a method of sensing characteristics, capacitance-voltage at the Schottky transition using a mercury probe.

In practice, a standard method of sensing capacitance-voltage characteristics is used to determine the concentration profile of active ingredients in the structure of silicon and gallium arsenide semiconductors, the so-called C-V method for measuring the Schottky transition using a mercury probe. This method is difficult to apply indium phosphide to the semiconductor because it has a small band gap. The problem is solved by creating a structure containing a serial combination of a metal-dielectric semiconductor, called a MIS structure, thereby increasing the potential barrier and measuring the epitaxial structure can be performed by the standard C-V method. The necessary insulating layer can be formed by oxidizing the surface of the epitaxial structure of indium phosphide during several hours of exposure of the surface of the epitaxial layer to the atmosphere or by immersing the epitaxial layer for a period of time. longer than two minutes to a 4% etching solution of bromine in methanol followed by multiple washes in redistilled water and drying. The disadvantage of the first method is the long duration of oxidation of the surface of the epitaxial structure, the disadvantage of the second method is the necessity to use a solution of bromine in methanol, where bromine is not cheap or commercially available chemical and methanol is strongly poisonous. As the solution is volatile and volatile, harmful fumes escape into the air, working with it requires the necessary precautions to be taken and, in addition, it must be prepared shortly before each measurement. A further disadvantage is that the etching operation and multiple surface washing of the brittle indium-phosphide structures while cleaning from the etchers result in a partial removal of the epitaxial layer, thereby significantly deteriorating the surface quality of the epitaxial structure and hence the measurement accuracy.

265 840

These disadvantages are largely eliminated by the method of adjusting the epitaxial structure of indium phosphide prior to measurement by the method of sensing the capacitance-voltage characteristics at the Schottky transition using the mercury probe of the invention, which comprises immersing a substrate with deposited n-type conductivity epitaxial structure in redistilled water , heated to boiling for lei 2 minutes.

An advantage of the method of treating the epitaxial layer according to the invention over the first method described in the prior art is the significant reduction of time losses prior to measurement. The advantage over the latter method is primarily to improve the accuracy and reproducibility of the epitaxial structure measurement results. At the same time, since there is no need to etch and wash several times the surface of brittle indium phosphide structures when cleaning from the etch, and the surface of the epitaxial layer is not removed, the quality surface of the epitaxial structure remains largely dependent on the quality of the microwave elements made therefrom. Another advantage is that boiling redistilled water as the oxidizing agent used eliminates the need to introduce special precautions.

An exemplary embodiment of treating the epitaxial layer prior to measuring the epitaxial structure will be described on a sample of an indium phosphide substrate having an epitaxial n-type conductivity structure deposited therein to measure the concentration profile of the active ingredients in the indium phosphide structure and epitaxial thickness. The sample is placed in a Teflon holder, which is immersed in a heated beaker of boiling redistilled water for 1 to 2 minutes, during which the boiling water released reacts with the indium and phosphorus epitaxial structures and forms an insulating layer of indium oxide and oxide on the epitaxial layer. After this time, the substrate sample holder is removed from boiling water, dried with a stream of pure nitrogen until ready for measurement. The surface quality of the epitaxial structure in this method of treatment of the epitaxial layer, which largely depends on the reproducibility of the C-V measurement, is maintained.

Claims (1)

SUBJECT OF THE INVENTION 265 840 Method for treating an epitaxial layer prior to measuring the epitaxial structure of indium phosphide by a Capturing Capacitance Schottky characteristic by means of a mercury probe, characterized in that the substrate coated with the epitaxial n-structure of n-type conductivity is immersed in redistilled water heated to boiling point one to two minutes.